Tumor Cells and the Onset of Cancer By: Amie M. Hacker The Statistics Cancer causes approximately 1/5th of the deaths in the United States each year. I. a. II. In 2001, cancer accounted for 553,768 of all deaths in the U.S. This is 22.9 % Worldwide, between 100 and 350 of every 100,000 people die of cancer. Men v. Women (The Statistics cont…) I. II. Breast Cancer is the leading cancer among white and African American women. a. Every three minutes a woman in the United States is diagnosed with breast cancer. Prostate Cancer is the third most common cause of death in males. a. More than 300,000 men lose their lives each year due to Prostate Cancer. Background Information of Cancer I. Cancer is due to a failure in the mechanisms that usually control the growth and production of cells II. When a cancer is present, normal cell birth and death rate is disrupted. III. The losses of cellular regulation gives rise to most or all cases of cancer. This is due to genetic damages. Background cont… IV. A mutation in two classes of genes is implicated in the onset of cancer. a. Proto-oncogenes b. Tumor-suppressor genes V. Gene from both of these classes encode proteins that help regulate cell birth or cell death. Proto-oncogenes (Background cont…) I. They are activated by mutations to become oncogenes. II. This mutation will cause the gene to become excessively active in growth. III. This can be caused by either an increase in gene expression or by the production of a hyperactive product. Tumor-suppressor gene (Background cont…) I. II. Under normal conditions, these genes are used to restrain the growth of cells, until needed. When tumor-suppressor genes are damaged, the cells are unrestrained and have inappropriate growth. Six Changes that Lead to Cancer I. II. III. IV. V. VI. Self-sufficient in growth signals Insensitivity to antigrowth signals Evasion of apoptosis Limitless replicative potential Tissue invasion and metastasis Sustained antigenesis Tumors I. Definitions a. Tumor b. Metastasis c. Benign d. Malignant e. Stem cells Metastic Tumor Cells are Invasive and Can Spread I. II. III. IV. Especially in older people, tumors are more frequent, but they do not usually pose a threat. These are called benign. These tumors may function as normal cells. They have a fibrous capsule. Benign tumors only become problems when their size interferes with normal function Metastic Tumor cont… I. The picture shows a benign skull tumor. Metastic Tumor cont… V. Malignant tumors usually divide and grow more rapidly than normal, fail to die at normal rate, or invade a nearby tissue. a. They may remain localized for a time period. b. They may also acquire the ability to metastasize. How Metastic Tumors Spread I. II. III. Normal cells are restricted to their place in the organ or tissue. Physical barriers, such as the basal lamina, prevent cells from traveling to different areas of the tissue. Cancer cells are able to degrade the basal lamina and penetrate other cells and areas of the tissue. How Metastic Tumors Spread cont… IV. Cancer cells may secrete a protein that converts the serum protein plasminogen to the active protease plasmin. V. As the basal lamina degrades, some of the tumor cell will enter the blood stream, but fewer than 1 in 10,000 survive and are able to create a secondary, metastic tumor. Cancers Usually Originate From Proliferating Cells I. For oncogenic mutations to provoke cancer, they must occur in dividing cells. II. Precursor cells initiate tumor growth. III. As differentiated cells die, they are replaced by proliferation of stem cells. Stem cells are capable of transforming into tumor cells. Cancers Usually Originate From Proliferating Cells cont… IV. Since stem cell divide throughout the life time, oncogenic mutations in the DNA can accumulate and transform into cancer cells. Tumor Growth Requires Formation of New Blood Vessels I. II. Tumors require new blood vessels in order to grow. a. In the absence of blood, the tumor can grow into a mass of about 106 cells. Most tumors induce the formation of new blood vessels. These blood vessels will invade the tumor and, in turn, nourish it. This is called angiogenesis. Tumor Growth cont… III. Process of Angiogenesis a. Degradation of the basal lamina b. Migration of the endothelial cells into the tumor c. Division of the endothelial cells d. Formation of a new basement membrane Review and Questions I. Review a. What is cancer? b. Types of Mutations c. Three ways tumors grow and cause the onset of cancer II. Questions?